DE102021128688B3 - Assembly leakage detection module and assembly leakage detection method - Google Patents

Abstract

A module (14) for detecting a leakage, comprising a pressure sensor (8) and a pump (2) for generating pressure, is in view of the task of detecting a leakage of an arrangement having a large sealed volume with a compact device to be reliably detected and/or quantified, characterized in that the module (14) has a lockable reference volume (11) which can be flow-connected to a tank connection (10) by means of a valve (9) and can be separated from it in a flow-tight manner, the pressure can be detected within the reference volume (11) by the pressure sensor (8), with pressure being able to be generated within the reference volume (11) by means of the pump (2) and with the reference volume (11) being controlled by means of a shut-off valve (4) via a reference orifice (5). a defined flow cross-section with an atmosphere outlet (1) can be connected in a flow-conducting manner and can be separated from it.

Description

The invention relates to a module according to the preamble of claim 1.

From the US 2015/0 082 866 A1 such a module is known. the US 2003/0 192 370 A1 discloses another module for error diagnosis.

High demands are placed on tank systems in motor vehicles in particular with regard to their tightness in order to prevent fuel or fuel vapors from escaping unintentionally. For this are from the DE 197 02 584 C2 , DE 197 55 401 C2 and DE 195 27 367 C2 Diagnostic methods have become known with which leaks can be detected.

In particular, methods are already known from the prior art in which leaks in a tank system are determined by means of a pressure drop. It is known, for example, to apply an overpressure to the volume to be examined and then to record the manner in which this overpressure is reduced. From the results it is possible to conclude the presence of a leak and even roughly its size.

A disadvantage of the known systems and methods is that their measurement results lead to relatively imprecise assumptions about the leakage variables. A leakage size can therefore be determined which, according to the existing measurement results, is too large, although the leakage size actually present would still satisfy a permissible limit value. This is how misdiagnoses can happen.

The invention is therefore based on the object of reliably detecting and/or quantifying a leak in an arrangement that has a large sealed volume using a compact device.

The present invention solves the aforementioned problem by the features of claim 1.

According to the invention, it was first recognized that a module for detecting a leakage must be provided with a reference volume that can be sealed in a fluid-tight manner in order to be able to carry out a self-diagnosis of the module. In this way it can be checked whether the module itself introduces a leak into an arrangement to be checked.

Furthermore, it has been recognized that with a reference volume, which can be optionally connected to a tank or separated from it, pressure conditions and their chronological progressions can be selectively recorded in a small volume and in a correspondingly large volume by using a compact device, namely the Module can be integrated into an existing system.

It has also been recognized that the pressure sensor can be used not only to detect the pressure or the time profile of a pressure drop or pressure increase in the reference volume, but also the pressure conditions in a tank that is connected to the tank connection as a large volume.

It has also been recognized that the pump can be used to selectively set pressures at different positions of the valves used in the module. The area of a leak can be determined from the pressure conditions and their time curves, taking into account a reference orifice, namely the area through which fluid can flow out of a volume of an arrangement.

With the invention described here, the diameter of the area of a leak can be determined with an accuracy of plus or minus 15%.

According to the invention, in a first position of the valve, the tank connection is connected to the atmosphere via an atmosphere outlet and separated from the reference volume, and in a second position it is connected to the reference volume and separated from the atmosphere outlet. A tank can be connected to the reference volume or separated from it by just one valve. The tank can also be vented to atmosphere by connecting the tank port. The valve is therefore advantageously designed as a switching valve.

The reference volume could be fluidly connected to the atmosphere outlet by means of a shut-off valve, with a flow line being provided which extends from the reference volume to the atmosphere outlet, in which the reference orifice is provided with a defined flow cross section. The reference orifice can be used to achieve a throttling effect when fluid flows out into the atmosphere. The throttling effect can be adjusted by adjusting the flow cross section. The reference volume can be vented when the shut-off valve is open. It is also conceivable to additionally vent the tank by opening the shut-off valve.

The atmosphere outlet could open into a filter through which fluid can flow into the atmosphere. The filter is preferably designed as a dust filter. This can prevent dust from penetrating the module and/or the tank from the environment.

A check valve could be arranged between the reference volume and the pump, which prevents backflow from the reference volume to the pump. In this way, a pressure in the reference volume can be reliably maintained when the pump is switched off. Self-diagnosis of the module is facilitated. Leaks in the reference volume, the non-return valve, the shut-off valve, the pressure sensor and/or the switching valve can be determined. Another advantage of the structural arrangement of the non-return valve is that the pump does not have to be "tight", namely the pump does not have to start up against pressure.

Furthermore, the non-return valve facilitates the fact that pressures can level off at a constant value and can then be kept constant. Against this background, it must be taken into account that a higher pressure is initially built up, but that this levels off at a constant, probably lower, value after the reaction and expansion of all parts of the pressure-loaded system.

The module could have a base body that has a tank connection for flange-mounting to an arrangement with a tank, the base body having an atmosphere outlet for discharging fluid into the atmosphere, and the base body having a module control unit with an interface for connecting to the electronics of a motor vehicle or another system to output information about a leak. Such a module can be adapted to any tank system and flanged on as an independent, compact device. The module is a self-sufficient structural unit and does not require any elements such as valves, measuring orifices, measuring tubes or pressure sensors in the vehicle itself. Furthermore, the module control unit ensures the integration of the electronics for controlling the measurement process and for evaluating the measurement within the module. The module control device preferably only gives complete information to the electronics of the motor vehicle or to an on-board computer.

Specifically, the module could be flanged to an activated carbon filter that is connected to a tank.

The module described here can also be used outside of automotive applications, for example in industry, where leaks from containers have to be determined and recorded.

An arrangement, which includes a module of the type described here, could also include a tank of a motor vehicle, which is connected to the tank connection with an activated charcoal filter interposed, with a line leading from the activated charcoal filter to the engine of the motor vehicle, which can be shut off or opened by a regeneration valve . As an option, a fuel vapor retention valve is installed in the line leading from the tank to the activated carbon filter. Purge valves are used to degas or vent the automobile's canister. Valves of this type are used to meter fuel vapor from the vehicle's carbon canister. In such an arrangement, a method for detecting a leakage of the arrangement can be carried out.

Against this background, a method for detecting a leak in an arrangement with a tank could be carried out using a module of the type described here, in which at least one pressure drop in a volume comprising the reference volume and the tank is measured. The module can be subjected to a self-diagnosis, so that after determining its tightness, an area within the arrangement, in particular the tank, can be determined through which fluid can flow out. As part of the self-diagnosis, a leakage measurement of the reference volume is carried out to ensure that the changeover valve is in the correct position after the measurement process and thus the connection between the tank and the atmosphere is secured.

• - Erfassen eines ersten Druckabfalls mittels des Drucksensors, wenn das unter Überdruck stehende Referenzvolumen mit der Atmosphäre verbunden wird und Fluid aus dem Referenzvolumen über die Referenzblende in die Atmosphäre abströmt,
• - Erfassen eines zweiten Druckabfalls im unter Überdruck stehenden Referenzvolumen, welches mit dem Tank verbunden ist,
• - Erfassen eines dritten Druckabfalls, wobei zwischen dem unter Überdruck stehenden Referenzvolumen, dem mit diesem verbundenen Tank und der Atmosphäre eine fluidleitende Verbindung besteht, so dass Fluid vom Tank und/ oder vom Referenzvolumen kommend über die Referenzblende in die Atmosphäre abströmen kann.

A method, namely a diagnostic method, of the following types could be carried out with the module. The procedure could include the following steps:

• - detecting a first drop in pressure by means of the pressure sensor when the reference volume, which is under overpressure, is connected to the atmosphere and fluid flows out of the reference volume via the reference orifice into the atmosphere,
• - detecting a second pressure drop in the pressurized reference volume connected to the tank,
• - Detection of a third pressure drop, with a fluid-conducting connection between the pressurized reference volume, the tank connected to it and the atmosphere, so that fluid can flow out of the tank and/or from the reference volume via the reference orifice into the atmosphere.

A pressure drop measurement is carried out in each step, so that a pressure drop is measured three times by the method.

The first pressure drop is caused by fluid flowing out of the reference volume via the reference orifice, the second pressure drop is caused by fluid flowing out of the reference volume and the volume of the tank via a leak area to be determined, and the third pressure drop is caused by fluid flowing out of the reference volume and the volume of the tank over a leak area to be determined, as well as the reference orifice. The size of the area of the leak can be determined in particular with knowledge of the reference diaphragm, although this knowledge is not absolutely necessary. The diameter of the reference diaphragm is preferably in the range from 0.1 mm to 0.8 mm.

• - Herstellen einer fluidleitenden Verbindung zwischen dem Tank und der Atmosphäre bei Abtrennung des Referenzvolumens von der Atmosphäre und vom Tank bei ausgeschalteter Pumpe,
• - Herstellen einer fluidleitenden Verbindung zwischen Referenzvolumen und Tank unter Trennung der Verbindung des Tanks mit der Atmosphäre, wobei ein Druck im Referenzvolumen und im Tank bei eingeschalteter Pumpe aufgebaut wird,
• - Konstant halten des Drucks bei eingeschalteter Pumpe,
• - Abschalten der Pumpe und mittels des Drucksensors prüfen, ob ein Druckabfall über eine Leckage der Anordnung oder des Tanks erfolgt,
• - Trennen der fluidleitenden Verbindung zwischen dem Referenzvolumen und dem Tank unter Herstellung einer fluidleitenden Verbindung zwischen Tank und Atmosphäre und Herstellen einer fluidleitenden Verbindung zwischen Referenzvolumen und Atmosphäre, bei ausgeschalteter Pumpe,
• - Trennen der fluidleitenden Verbindung zwischen dem Referenzvolumen und der Atmosphäre und Herstellen einer fluidleitenden Verbindung zwischen Tank und Referenzvolumen unter Abtrennung der fluidleitenden Verbindung des Tanks mit der Atmosphäre, so dass ein Druckanstieg im Referenzvolumen und im Tank bei ausgeschalteter Pumpe durch Verdampfung des Fluids entsteht,
• - Trennen der fluidleitenden Verbindung zwischen dem Referenzvolumen und dem Tank unter Herstellung einer fluidleitenden Verbindung zwischen Tank und Atmosphäre, so dass eine Entlüftung des Tanks bei ausgeschalteter Pumpe erfolgt, und Herstellung einer fluidleitenden Verbindung zwischen Referenzvolumen und Atmosphäre bei ausgeschalteter Pumpe,
• - Trennen der fluidleitenden Verbindung zwischen Referenzvolumen und Atmosphäre und Bestimmung eines Offsets des Drucksensors bei ausgeschalteter Pumpe.

The method could also include the following steps, essentially using the second pressure drop measurement of the leak detection method previously described:

• - establishing a fluid-conducting connection between the tank and the atmosphere when separating the reference volume from the atmosphere and from the tank when the pump is switched off,
• - Establishing a fluid-conducting connection between the reference volume and the tank while separating the connection between the tank and the atmosphere, with a pressure being built up in the reference volume and in the tank when the pump is switched on,
• - keeping the pressure constant when the pump is switched on,
• - switch off the pump and check by means of the pressure sensor whether there is a pressure drop via a leak in the arrangement or the tank,
• - Disconnecting the fluid-conducting connection between the reference volume and the tank to establish a fluid-conducting connection between the tank and the atmosphere and establishing a fluid-conducting connection between the reference volume and the atmosphere when the pump is switched off,
• - Separating the fluid-conducting connection between the reference volume and the atmosphere and establishing a fluid-conducting connection between the tank and the reference volume while separating the fluid-conducting connection of the tank with the atmosphere, so that a pressure increase in the reference volume and in the tank occurs when the pump is switched off due to evaporation of the fluid,
• - Disconnecting the fluid-conducting connection between the reference volume and the tank while establishing a fluid-conducting connection between the tank and the atmosphere, so that the tank is vented when the pump is switched off, and establishing a fluid-conducting connection between the reference volume and the atmosphere when the pump is switched off,
• - Disconnecting the fluid-conducting connection between the reference volume and the atmosphere and determining an offset of the pressure sensor when the pump is switched off.

A shortened procedure can thus be carried out.

• - Herstellen einer fluidleitenden Verbindung zwischen dem Tank und der Atmosphäre bei Abtrennung des Referenzvolumens von der Atmosphäre und vom Tank bei ausgeschalteter Pumpe,
• - Aufbauen eines Drucks im Referenzvolumen, welches vom Tank und der Atmosphäre fluiddicht getrennt ist, bei eingeschalteter Pumpe,
• - Überprüfung der Dichtheit des Referenzvolumens und des Moduls mittels des Drucksensors bei ausgeschalteter Pumpe,
• - Herstellen einer fluidleitenden Verbindung zwischen dem Referenzvolumen und der Atmosphäre, so dass Fluid über die Referenzblende in die Atmosphäre abströmen kann, bei eingeschalteter Pumpe,
• - Konstant Halten des Drucks, der von der eingeschalteten Pumpe gegen die Referenzblende aufgebaut wird,
• - Abschalten der Pumpe und Überprüfen des Druckabfalls über die Referenzblende mittels des Drucksensors,
• - Herstellen einer fluidleitenden Verbindung zwischen Referenzvolumen und Tank unter Trennung der Verbindung sowohl des Tanks als auch des Referenzvolumens mit der Atmosphäre, so dass kein Abströmen von Fluid in die Atmosphäre über die Referenzblende mehr möglich ist, wobei ein Druck im Referenzvolumen und im Tank bei eingeschalteter Pumpe aufgebaut wird,
• - Konstant Halten des Drucks bei eingeschalteter Pumpe,
• - Abschalten der Pumpe und mittels des Drucksensors prüfen, ob ein Druckabfall über eine Leckage der Anordnung oder des Tanks erfolgt,
• - Herstellen einer fluidleitenden Verbindung zwischen dem Referenzvolumen, dem Tank und der Atmosphäre, so dass Fluid vom Tank und/ oder vom Referenzvolumen kommend über die Referenzblende in die Atmosphäre bei eingeschalteter Pumpe abströmen kann, wobei die Pumpe einen Druck aufbaut,
• - Konstant Halten des Drucks bei eingeschalteter Pumpe,
• - Ausschalten der Pumpe unter Beibehalten der fluidleitenden Verbindung zwischen dem Referenzvolumen, dem Tank und der Atmosphäre, so dass Fluid vom Tank und/ oder vom Referenzvolumen kommend über die Referenzblende in die Atmosphäre abströmen kann,
• - Trennen der fluidleitenden Verbindung zwischen dem Referenzvolumen und dem Tank unter Herstellung einer fluidleitenden Verbindung zwischen Tank und Atmosphäre, so dass Fluid vom Tank kommend in die Atmosphäre abströmen kann und ein Entlüften des Tanks bei ausgeschalteter Pumpe erfolgt,
• - Trennen der fluidleitenden Verbindung zwischen dem Referenzvolumen und der Atmosphäre und Herstellen einer fluidleitenden Verbindung zwischen Tank und Referenzvolumen unter Abtrennung der fluidleitenden Verbindung des Tanks mit der Atmosphäre, so dass ein Druckanstieg im Referenzvolumen und im Tank bei ausgeschalteter Pumpe durch Verdampfung des Fluids entsteht,
• - Trennen der fluidleitenden Verbindung zwischen dem Referenzvolumen und dem Tank unter Herstellung einer fluidleitenden Verbindung zwischen Tank und Atmosphäre, so dass eine Entlüftung des Tanks bei ausgeschalteter Pumpe erfolgt, und Herstellung einer fluidleitenden Verbindung zwischen Referenzvolumen und Atmosphäre bei ausgeschalteter Pumpe,
• - Trennen der fluidleitenden Verbindung zwischen Referenzvolumen und Atmosphäre und Bestimmung eines Offsets des Drucksensors bei ausgeschalteter Pumpe.

A very precise method of detecting a leak in a single tank arrangement could include the following steps:

• - establishing a fluid-conducting connection between the tank and the atmosphere when separating the reference volume from the atmosphere and from the tank when the pump is switched off,
• - Build up a pressure in the reference volume, which is fluid-tightly separated from the tank and the atmosphere, with the pump switched on,
• - checking the tightness of the reference volume and the module using the pressure sensor with the pump switched off,
• - Creation of a fluid-conducting connection between the reference volume and the atmosphere so that fluid can flow through the reference orifice into the atmosphere when the pump is switched on,
• - Keeping the pressure constant, which is built up by the switched-on pump against the reference orifice,
• - switching off the pump and checking the pressure drop across the reference orifice using the pressure sensor,
• - Creation of a fluid-conducting connection between the reference volume and the tank while separating the connection of both the tank and the reference volume with the atmosphere, so that no outflow of fluid into the atmosphere via the reference orifice is possible, whereby a pressure in the reference volume and in the tank is switched on pump is built,
• - Keeping the pressure constant when the pump is switched on,
• - switch off the pump and check by means of the pressure sensor whether there is a pressure drop via a leak in the arrangement or the tank,
• - Making a fluid-conducting connection between the reference volume, the tank and the atmosphere, so that fluid coming from the tank and / or from the reference volume on the reference orifice can flow into the atmosphere when the pump is switched on, whereby the pump builds up a pressure
• - Keeping the pressure constant when the pump is switched on,
• - switching off the pump while maintaining the fluid-conducting connection between the reference volume, the tank and the atmosphere, so that fluid coming from the tank and/or the reference volume can flow out via the reference orifice into the atmosphere,
• - Disconnecting the fluid-conducting connection between the reference volume and the tank while establishing a fluid-conducting connection between the tank and the atmosphere, so that fluid coming from the tank can flow out into the atmosphere and the tank is vented when the pump is switched off,
• - Separating the fluid-conducting connection between the reference volume and the atmosphere and establishing a fluid-conducting connection between the tank and the reference volume while separating the fluid-conducting connection of the tank with the atmosphere, so that a pressure increase in the reference volume and in the tank occurs when the pump is switched off due to evaporation of the fluid,
• - Disconnecting the fluid-conducting connection between the reference volume and the tank while establishing a fluid-conducting connection between the tank and the atmosphere, so that the tank is vented when the pump is switched off, and establishing a fluid-conducting connection between the reference volume and the atmosphere when the pump is switched off,
• - Disconnecting the fluid-conducting connection between the reference volume and the atmosphere and determining an offset of the pressure sensor when the pump is switched off.

The aforementioned steps are preferably carried out one after the other. The method carries out three pressure drop measurements, the evaluation of which always takes place in the same, approximately the same or essentially the same pressure range, so that a pressure-dependent measurement accuracy of the pressure sensor is eliminated.

A pressure is kept constant in the aforementioned methods during a pressure holding time with pressure control, so that the module and the arrangement can reach a stable state and level off in a pressure-stable manner.

The first step of establishing a fluid-conducting connection between the tank and the atmosphere when the reference volume is separated from the atmosphere and from the tank when the pump is switched off corresponds to the normal state of the module.

The step of separating the fluid-conducting connection between the reference volume and the atmosphere and determining an offset of the pressure sensor when the pump is switched off serves to restore the normal state of the module.

The method could preferably be carried out in a motor vehicle with the engine not running. As a result, the method can be carried out particularly precisely and the area of the leak can be determined particularly precisely. Diagnosis by the procedure described herein is performed only when the gas cap is closed, a purge valve is closed, an optional FTIV is open for full system diagnostics or a partial space is closed, and the engine is off is. However, it is also conceivable to carry out the method with the engine running.

The area of leakage of the assembly could be quantified and/or reported by the module. The gas volume in the tank can be calculated to check the plausibility of the determined leak area.

The diameter of an area of a leak, in particular an area assumed to be round, could be recorded with an accuracy of +/- 15%. The module described here is suitable for measuring the diameter with this level of accuracy.

• 1 eine schematische Ansicht eines Moduls, welches als bauliche Einheit sowohl mechanisch als auch elektronisch an eine Anordnung eines Tanksystems eines Kraftfahrzeugs angeschlossen werden kann,
• 2 eine Anordnung mit einem angeschlossenen Modul nach 1,
• 3 eine Darstellung des Ablaufs eines verkürzten Verfahrens zur Erfassung einer Leckage der Anordnung nach 2, und
• 4 eine Darstellung des Ablaufs eines präziseren Verfahrens zur Erfassung einer Leckage der Anordnung nach 2,
• 5 eine Auflistung der Schritte eines präzisen Verfahrens zur Erfassung einer Leckage nach 4, wobei der jeweilige Schaltzustand der relevanten Ventile und der Betriebsmodus der Pumpe während des jeweiligen Schritts und die jeweiligen Verhältnisse der physikalischen Größen während der einzelnen Schritte angezeigt sind, und
• 6 eine Darstellung der Formeln, die bei der Ermittlung und Prüfung der Größe der Leckage verwendet werden.

Show in the drawing

• 1 a schematic view of a module, which as a structural unit can be connected both mechanically and electronically to an arrangement of a tank system of a motor vehicle,
• 2 an arrangement with a connected module 1 ,
• 3 an illustration of the sequence of an abbreviated method for detecting a leakage according to the arrangement 2 , and
• 4 an illustration of the sequence of a more precise method for detecting a leakage according to the arrangement 2 ,
• 5 a listing of the steps of a precise procedure for detecting a leak 4 , The respective switching state of the relevant valves and the operating mode of the pump during the respective step and the respective ratios of the physical cal quantities are displayed during the individual steps, and
• 6 an illustration of the formulas used in determining and testing the size of the leak.

1 shows a module 14 for detecting a leak, comprising a pressure sensor 8 and a pump 2 for generating pressure.

The module 14 has a lockable reference volume 11, which can be flow-connected to a tank connection 10 by means of a valve 9 and can be separated from it in a flow-tight manner, the pressure within the reference volume 11 being able to be detected by the pressure sensor 8, the pressure within the reference volume 11 being measured by the pump 2 can be generated and wherein the reference volume 11 can be connected in a flow-conducting manner to an atmosphere outlet 1 by means of a shut-off valve 4 via a reference orifice plate 5 with a defined flow cross-section and can be separated therefrom.

The reference volume preferably has a volume between 20 and 100 ml. The tank connection 10 can be connected to a tank 15 according to FIG 2 or flanged to a line that comes from it. The pressure sensor 8 is connected to the reference volume 11 in such a way that the pressure within the reference volume 11 and in the tank 15 can be detected by the pressure sensor 8 . The pump 2 is connected to the reference volume 11 in such a way that pressure can be generated within it and in the tank 15 by means of the pump 2 . The pump 2 has a pump motor 3 .

In a first position of the valve 9 , the tank connection 10 is connected to the atmosphere via an atmosphere outlet 1 and is separated from the reference volume 11 , and in a second position it is connected to the reference volume 11 and separated from the atmosphere outlet 1 . The valve 9 is designed as a changeover valve.

The reference volume 11 can be flow-connected to the atmosphere outlet 1 by means of a shut-off valve 4, a flow line being provided which extends from the reference volume 11 to the atmosphere outlet 1, a reference orifice 5 with a diameter between 0.1 mm and 0.8 mm being installed in the flow line mm is provided. The flow line opens into a line with which the tank connection 10 can be connected to the atmosphere outlet 1 . The reference orifice 5 is arranged between the shutoff valve 4 and the reference volume 11 .

2 shows that the atmosphere outlet 1 opens into a filter 13, namely a dust filter, through which fluid can flow into the atmosphere.

A non-return valve 12 is arranged between the reference volume 11 and the pump 2 and prevents a backflow from the reference volume 11 to the pump 2 . Only four outlets for a fluid lead away from the reference volume 11 . A first outlet leads to reference orifice 5, a second to the non-return valve or in the direction of pump 2 and a third to tank connection 10. A fourth outlet ends in pressure sensor 8.

1 and 2 show that the module 14 has a base body which has a tank connection 10 for flange connection to an arrangement with a tank 15 . The tank connection 10 can be flanged directly to a tank 15 or directly to a line extending from this, or the tank connection 10 can be connected with an activated charcoal filter 16, as is shown in 2 is shown to be flanged to a tank 15.

The base body has an atmosphere outlet 1 for discharging fluid into the atmosphere. The base body has a module control device 6 with an interface 7 for connection to the electronics of a motor vehicle or another system in order to output information about a leak.

The module control device 6 includes measurement and control electronics. The module control device 6 can provide the information that the leakage is too high or not. Optionally, the module control device 6 can also output the size of the area of the leak as information.

2 shows an arrangement comprising the module 14 and a tank 15 of a motor vehicle, which is connected to the tank connection 10 with an activated charcoal filter 16 being connected in between, with a line leading from the activated charcoal filter 16 to the motor 17 of the motor vehicle, which can be shut off or opened by a regeneration valve 18 .

Another line leads from the tank 15 to the activated charcoal filter 16, with an FTIV, namely a valve 19 for retaining fuel vapors, being arranged in this further line. Although in 2 an FTIV is shown, this can also be missing. The FTIV is an optional component.

In that regard, the further line leads from the tank 15 to the FTIV for the activated carbon filter 16 and go from the activated carbon filter 16 two lines, namely one via the regeneration valve 18 to the motor 17 and one to the module 14, which with the Reference volume 11 can be fluidly connected via the valve 9 .

The module 14 can be flanged onto the arrangement with the tank 15 as a preassembled structural unit. There are preferably only three connections, a mechanical tank connection 10, a mechanical connection to the atmosphere, namely the atmosphere outlet 1, and an electronic connection, which is represented by the interface 7.

• Schritt S1: Herstellen einer fluidleitenden Verbindung zwischen dem Tank 15 und der Atmosphäre bei Abtrennung des Referenzvolumens 11 von der Atmosphäre und vom Tank 15 bei ausgeschalteter Pumpe 2. Schritt S1 zeigt den Normalzustand, bei dem der Tank 15 mit der Atmosphäre in Kontakt steht.
• Schritt S2 zeigt den Druckaufbau durch die Pumpe 2. Es erfolgt ein Aufbauen eines Drucks im Referenzvolumen 11, welches vom Tank 15 und der Atmosphäre fluiddicht getrennt ist, bei eingeschalteter Pumpe 2. Wenn kein Druck aufgebaut wird, ist die Pumpe 2 defekt. Wenn der Druck nur langsam aufgebaut wird, ist das Umschaltventil geöffnet oder die Spannung für die Pumpe 2 ist zu gering.

4 and 5 schematically show a method for detecting a leak in an arrangement with a tank 15 using the module 14, which comprises the following steps:

• Step S1: establishment of a fluid-conducting connection between the tank 15 and the atmosphere when the reference volume 11 is separated from the atmosphere and from the tank 15 with the pump 2 switched off. Step S1 shows the normal state in which the tank 15 is in contact with the atmosphere.
• Step S2 shows the pressure build-up by the pump 2. A pressure builds up in the reference volume 11, which is fluid-tightly separated from the tank 15 and the atmosphere, when the pump 2 is switched on. If no pressure is built up, the pump 2 is defective. If the pressure builds up slowly, the switching valve is open or the voltage for pump 2 is too low.

Step S3 measures the tightness of the reference volume 11. The tightness of the reference volume 11 and thus of the module 14 is checked using the pressure sensor 8 when the pump 2 is switched off. If the pressure drop is too high, the module 14 is leaking. If the pressure drop is very high, the shut-off valve 4 may be open.

The shut-off valve 4 is opened by step S4 and pressure is built up against the reference orifice 5 . A fluid-conducting connection is established between the reference volume 11 and the atmosphere, so that fluid can flow out into the atmosphere via the reference orifice 5 when the pump 2 is switched on. If the pressure does not drop, then the shut-off valve 4 is closed.

In step S5, the pressure against the reference diaphragm 5 is kept constant after the pressure has leveled off, so that it is set to a constant value or a value that is as constant as possible. The pressure that is built up by the switched-on pump 2 against the reference orifice 5 is kept constant. If the pump flow is too low, the reference orifice 5 is heavily soiled since the pressure is regulated to a constant value.

A self-diagnosis of the module 14 takes place through steps S2 to S5, which includes checking the pump 2, the valve 9, namely the changeover valve, the shut-off valve 4, the reference orifice 5 and the pressure sensor 6. The module 14 is checked overall.

In step S6, pump 2 is switched off and the pressure drop across reference orifice 5 is checked by pressure sensor 8. Pressure sensor 8 measures pressure value Δp _{0 at time t 0 and} pressure value Δp ₁ at time t ₁ . The same takes place in steps S9 and S12. A pressure value is measured because a differential pressure sensor is used as the pressure sensor 8 . A drop in pressure is measured between two points in time or between two pressure values, namely two differential pressure values.

In step S7, a fluid-conducting connection is established between the reference volume 11 and the tank 15, with the connection between the tank 15 and the reference volume 11 being separated from the atmosphere, so that fluid can no longer flow into the atmosphere via the reference orifice plate 5, with a pressure is built up in the reference volume 11 and in the tank 15 when the pump 2 is switched on.

In step S8, the pressure is kept constant with pump 2 switched on.

In step S9, the pump 2 is switched off and the pressure sensor 6 is used to check whether there is a drop in pressure due to a leak in the arrangement or in the tank 15. A pressure value Δp _{2 is measured by the pressure sensor 8 at time t 2 and} a pressure value Δp ₃ is measured at time t ₃ .

In step S10, a fluid-conducting connection is established between the reference volume 11, the tank 15 and the atmosphere, so that fluid coming from the tank 15 and/or from the reference volume 11 can flow out via the reference orifice 5 into the atmosphere when the pump motor 3 of the pump 2 is switched on , wherein the pump 2 builds up a pressure.

In step S11, the pressure is kept constant when pump 2 is switched on or when pump motor 3 is switched on.

In step S12, the pump 2 is switched off while maintaining the fluid-conducting connection between the reference volume 11, the tank 15 and the atmosphere, so that fluid from the tank 11 and/or from the reference volume 11 comes over the reference aperture 5 can flow into the atmosphere. A pressure value Δp _{4 is measured by the pressure sensor 8 at time t 4 and} a pressure value Δp ₅ is measured at time t ₅ .

Steps S6, S9 and S12 result in a pressure drop measurement in each case, so that a pressure drop is measured three times by the method.

The first pressure drop occurs due to the outflow of fluid from the reference volume 11 via the reference orifice 5, the second pressure drop occurs due to the outflow of fluid from the reference volume 11 and volume of the tank 15 via an area of a leak to be determined, and the third pressure drop occurs due to the outflow of fluid from the reference volume 11 and the volume of the tank 15 over an area of a leak to be determined and over the reference orifice 5.

In step S13, the fluid-conducting connection between the reference volume 11 and the tank 15 is separated, creating a fluid-conducting connection between the tank 15 and the atmosphere, so that fluid coming from the tank 15 can flow out into the atmosphere and the tank 15 can be vented when the pump 2 is switched off he follows.

In step S14, the fluid-conducting connection between the reference volume 11 and the atmosphere is separated and a fluid-conducting connection is established between tank 15 and reference volume 11, with the fluid-conducting connection of tank 15 being separated from the atmosphere, so that a pressure increase in reference volume 11 and in tank 15 caused by evaporation of the fluid when pump 2 is switched off. Step S14 therefore describes an increase in pressure due to evaporation.

Step S15 describes a disconnection of the fluid-conducting connection between the reference volume 11 and the tank 15 to establish a fluid-conducting connection between the tank 15 and the atmosphere, so that the tank 15 is vented when the pump 2 is switched off, and the establishment of a fluid-conducting connection between the reference volume 11 and atmosphere when pump 2 is switched off. Step S15 therefore describes venting.

In step S16, the fluid-conducting connection between the reference volume 11 and the atmosphere is separated and an offset of the pressure sensor 6 is determined when the pump 2 is switched off.

The method described here is carried out in a motor vehicle when the engine 17, which is an internal combustion engine, is not running.

The area of the leakage of the arrangement is quantitatively determined and output by the module 14, namely passed on via the interface 7 to the electronics of the motor vehicle. To determine the area quantitatively, the following formula can be used, which can also be found in 6 is shown:

A_TL- Fläche des gesamten Tanklecks, α - ein Durchflusskoeffizient, patm - atmosphärischer Druck, R_S - spezifische Gaskonstante, T - Temperatur des Fluids oder Gases in K, V_Ref - Inneres Volumen oder Referenzvolumen 11 des Moduls 14Leak area: $$A_{TL}=\frac{\frac{V_{Ref}\cdot \left(\Delta p_0-\Delta p_1\right)}{a\cdot \sqrt{p_{atm}}\cdot \sqrt{R_s\cdot T}\cdot \left({\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="DE102021128688B3\_0006.png,DE102021128688B3\_0007.png"\; state="\{\{state\}\}">t</figure-callout>}}_1-t_0\right)\cdot \sqrt{\Delta p_0-\Delta p_1}}}{\frac{\left(\mathrm{<figure-callout\; id="4"\; label="\Delta \; p"\; filenames="DE102021128688B3\_0003.png,DE102021128688B3\_0006.png"\; state="\{\{state\}\}">\Delta </figure-callout>}{p}_{}{}_4-\Delta p_5\right)\cdot \sqrt{\mathrm{<figure-callout\; id="2"\; label="\Delta \; p"\; filenames="DE102021128688B3\_0003.png,DE102021128688B3\_0007.png"\; state="\{\{state\}\}">\Delta </figure-callout>}{p}_{}{}_2-\mathrm{<figure-callout\; id="3"\; label="\Delta \; p"\; filenames="DE102021128688B3\_0003.png"\; state="\{\{state\}\}">\Delta </figure-callout>}{p}_{}{}_3}\cdot \left({\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="DE102021128688B3\_0003.png"\; state="\{\{state\}\}">t</figure-callout>}}_3-t_2\right)}{\left(\mathrm{<figure-callout\; id="2"\; label="\Delta \; p"\; filenames="DE102021128688B3\_0003.png,DE102021128688B3\_0007.png"\; state="\{\{state\}\}">\Delta </figure-callout>}{p}_{}{}_2-\Delta p_3\right)\cdot \sqrt{\mathrm{<figure-callout\; id="4"\; label="\Delta \; p"\; filenames="DE102021128688B3\_0003.png,DE102021128688B3\_0006.png"\; state="\{\{state\}\}">\Delta </figure-callout>}{p}_{}{}_4-\mathrm{<figure-callout\; id="5"\; label="\Delta \; p"\; filenames="DE102021128688B3\_0003.png,DE102021128688B3\_0006.png"\; state="\{\{state\}\}">\Delta </figure-callout>}{p}_{}{}_5}\cdot \left({\mathrm{<figure-callout\; id="5"\; label="t"\; filenames="DE102021128688B3\_0003.png,DE102021128688B3\_0006.png"\; state="\{\{state\}\}">t</figure-callout>}}_5-t_4\right)}-1}$$

A _TL - area of the entire tank leak, α - a flow coefficient, patm - atmospheric pressure, R _S - specific gas constant, T - temperature of the fluid or gas in K, V _Ref - internal volume or reference volume 11 of module 14

The flow coefficient is a parameter that takes into account all losses that occur when a fluid flows through an orifice.

The values for Δp and t, that is, the pressure values measured within the framework of pressure drops at specific times, and the times of their measurement associated with these are off 4 removable.

The method described above is carried out with a constant tank filling, in which case the level of the fuel in the tank 15 does not change.

A time reduction of the method described above or the diagnosis of the module 14 and / or the arrangement could be carried out by carrying out only one pressure drop measurement, namely the second according to 4 , to be realized like this in 3 is shown.

The values Δp ₀ and Δp ₁ in 3 correspond to the values Δp ₂ and Δp ₃ in 4 . The other two pressure drop measurements 4 are following the procedure 3 not done.

Under the approximate assumption of the worst case, namely that the gas volume in the tank 15 is at its maximum, with the diameter d _TL of an imaginary round area of the leak being «0.5 mm, it can be determined whether the diameter of the area of the leak of the tank « is 0.5mm.

The only pressure drop measured is due to fluid leaking from the reference volume 11 and the volume of the tank 15 across an area of a leak in the tank 15. At the end of this procedure it should be checked that the valve 9, namely the switching valve, is closed again due to pressure build-up in the reference volume 11.

The determined area of the leak can be subjected to a plausibility check.

The following simplified formula provides the calculated or estimated current gas volume V in tank 15: $$V=\frac{a\cdot {\mathrm{i.e}}_{T\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="DE102021128688B3\_0003.png,DE102021128688B3\_0007.png"\; state="\{\{state\}\}">L</figure-callout>}}{}^2\cdot \mathrm{\pi }\cdot \left({\text{<figure-callout id="2" label="t" filenames="DE102021128688B3\_0003.png,DE102021128688B3\_0007.png" state="{{state}}">t</figure-callout>}}_2-{\text{t}}_3\right)\cdot \sqrt{\frac{R_s\cdot \mathrm{<figure-callout\; id="2"\; label="T"\; filenames="DE102021128688B3\_0003.png,DE102021128688B3\_0007.png"\; state="\{\{state\}\}">T</figure-callout>}}{2}}}{4\cdot \left(\sqrt{\frac{\Delta p_3}{p_{atm}}-\sqrt{\frac{\Delta p_2}{p_{atm}}}}\right)}$$

It is thus possible to compare the currently measured gas volume with the level currently displayed by the motor vehicle's on-board computer and to subject the measured result for the area of the leak to a plausibility check.

The methods described here and the associated diagnoses are also possible using negative pressure. As far as generation of pressure is mentioned in this description, it is optionally also conceivable to generate negative pressure.

reference list

1

atmosphere exit

2

pump

3

pump motor from 2

4

shut-off valve

5

reference aperture

6

module controller

7

interface of 6

8th

pressure sensor

9

valve, changeover valve

10

tank connection

11

reference volume

12

check valve

13

filter

14

module

15

tank

16

activated carbon filter

17

engine, internal combustion engine

18

regeneration valve

19

FTIV

Claims (13)

Module (14) for detecting a leak, comprising a pressure sensor (8) and a pump (2) for generating pressure, the module (14) having a lockable reference volume (11) which is connected to a tank connection by means of a valve (9). (10) can be flow-connected and separated from it in a flow-tight manner, the pressure within the reference volume (11) being detectable by the pressure sensor (8), pressure being able to be generated within the reference volume (11) by means of the pump (2) and the reference volume (11 ) by means of a shut-off valve (4) via a reference orifice (5) with a defined flow cross-section can be connected in a flow-conducting manner to an atmosphere outlet (1) and can be separated from it, characterized in that the tank connection (10) in a first position of the valve (9) an atmosphere outlet (1) connected to the atmosphere and separated from the reference volume (11) and connected in a second position to the reference volume (11) and from Atmosp hair outlet (1) is disconnected. module after claim 1 , characterized in that a flow line is provided which extends from the reference volume (11) to the atmosphere outlet (1), in which the reference orifice (5) is provided with a defined flow cross section. Module according to one of the preceding claims, characterized in that the atmosphere outlet (1) opens into a filter (13) through which fluid can flow out into the atmosphere. Module according to one of the preceding claims, characterized in that a check valve (12) is arranged between the reference volume (11) and the pump (2), which prevents backflow from the reference volume (11) to the pump (2). Module according to one of the preceding claims, characterized by a base body which has a tank connection (10) for flange connection to an arrangement with a tank (15), wherein the base body has an atmosphere outlet (1) for discharging fluid into the atmosphere and wherein the Base body has a module control unit (6) with an interface (7) for connection to the electronics of a motor vehicle or another system in order to output information about a leak. Arrangement, comprising a module (14) according to one of the preceding claims and a tank (15) of a motor vehicle, which is connected to the tank connection (10) with the interposition of an activated charcoal filter (16), a line leading from the activated charcoal filter (16) to the engine (17) of the motor vehicle, which can be shut off or opened by a regeneration valve (18). Method for detecting a leak in an arrangement with a tank (15) using a module (14) according to one of Claims 1 until 5 , in which at least one pressure drop is measured in a volume comprising the reference volume (11) and the tank (15). procedure after claim 7 , characterized by the following steps: - detecting a first drop in pressure by means of the pressure sensor (8) when the reference volume (11) which is under overpressure is connected to the atmosphere and fluid from the reference volume (11) is released into the atmosphere via a reference orifice (5). flows out, - detection of a second pressure drop in the pressurized reference volume (11), which is connected to the tank (15), - detection of a third pressure drop, wherein between the pressurized reference volume (11), the tank (15 ) and the atmosphere there is a fluid-conducting connection, so that fluid coming from the tank (11) and/or from the reference volume (11) can flow out via the reference orifice (5) into the atmosphere. procedure after claim 7 , characterized by the following steps: - Establishing a fluid-conducting connection between the tank (15) and the atmosphere when separating the reference volume (11) from the atmosphere and from the tank (15) when the pump (2) is switched off, - Establishing a fluid-conducting connection between Reference volume (11) and tank (15) while separating the connection of the tank (15) with the atmosphere, whereby a pressure is built up in the reference volume (11) and in the tank (15) when the pump (2) is switched on, - keeping the pressure constant with the pump (2) switched on, - switch off the pump (2) and use the pressure sensor (6) to check whether there is a pressure drop via a leak in the arrangement or the tank (15), - disconnect the fluid-conducting connection between the reference volume (11) and the tank (15), producing a fluid-conducting connection between the tank (15) and the atmosphere and producing a fluid-conducting connection between the reference volume (11) and the atmosphere when the pump is switched off pe (2), - Separating the fluid-conducting connection between the reference volume (11) and the atmosphere and establishing a fluid-conducting connection between the tank (15) and the reference volume (11) while separating the fluid-conducting connection of the tank (15) with the atmosphere, so that a pressure increase in the reference volume (11) and in the tank (15) occurs when the pump (2) is switched off due to evaporation of the fluid, 15) and atmosphere, so that the tank (15) is vented when the pump (2) is switched off, and establishment of a fluid-conducting connection between the reference volume (11) and atmosphere when the pump (2) is switched off, - Separating the fluid-conducting connection between the reference volume (11 ) and atmosphere and determination of an offset of the pressure sensor (6) when the pump (2) is switched off. procedure after claim 7 , characterized by the following steps: - establishing a fluid-conducting connection between the tank (15) and the atmosphere when the reference volume (11) is separated from the atmosphere and from the tank (15) when the pump (2) is switched off, - building up a first pressure in the Reference volume (11), which is fluid-tightly separated from the tank (15) and the atmosphere, with the pump (2) switched on, - Checking the tightness of the reference volume (11) and the module (14) using the pressure sensor (8) with the pump switched off ( 2), - establishing a fluid-conducting connection between the reference volume (11) and the atmosphere, so that fluid can flow out into the atmosphere via a reference orifice (5) when the pump (2) is switched on, - keeping the pressure constant from the switched on pump (2) is built up against the reference orifice (5), - switching off the pump (2) and checking the pressure drop across the reference orifice (5) using the pressure sensor (8), - creating a fluid-conducting Connection between the reference volume (11) and tank (15) while separating the connection of both the tank (15) and the reference volume (11) to the atmosphere, so that fluid can no longer flow into the atmosphere via the reference orifice (5). , whereby a second pressure is built up in the reference volume (11) and in the tank (15) when the pump (2) is switched on, - the pressure is kept constant when the pump (2) is switched on, - the pump (2) is switched off and the pressure sensor (6 ) Check whether a pressure drop occurs via a leak in the arrangement or the tank (15), - establishing a fluid-conducting connection between between the reference volume (11), the tank (15) and the atmosphere, so that fluid coming from the tank (15) and/or from the reference volume (11) can flow out via the reference orifice (5) into the atmosphere when the pump (2) is switched on , whereby the pump (2) builds up a pressure, - keeping the pressure constant when the pump (2) is switched on, - switching off the pump (2) while maintaining the fluid-conducting connection between the reference volume (11), the tank (15) and the atmosphere , so that fluid coming from the tank (11) and/or from the reference volume (11) can flow out via the reference orifice (5) into the atmosphere, - separating the fluid-conducting connection between the reference volume (11) and the tank (15) to produce a fluid-conducting connection between the tank (15) and the atmosphere, so that fluid can flow from the tank (15) into the atmosphere and the tank is vented when the pump (2) is switched off, - disconnecting the fluid-conducting connection between the reference volume (11) and de r atmosphere and establishing a fluid-conducting connection between the tank (15) and reference volume (11) by separating the fluid-conducting connection of the tank (15) to the atmosphere, so that a pressure increase in the reference volume (11) and in the tank (15) when the pump ( 2) caused by evaporation of the fluid, - separating the fluid-conducting connection between the reference volume (11) and the tank (15) while establishing a fluid-conducting connection between the tank (15) and the atmosphere, so that the tank (15) can be vented when the pump is switched off (2) takes place, and establishing a fluid-conducting connection between the reference volume (11) and the atmosphere when the pump (2) is switched off, - separating the fluid-conducting connection between the reference volume (11) and the atmosphere and determining an offset of the pressure sensor (6) when the pump is switched off (2 ). Procedure according to one of Claims 7 until 10 , characterized in that this is carried out in a motor vehicle when the engine (17) is not running. Procedure according to one of Claims 7 until 11 , characterized in that the area of the leakage of the arrangement is quantitatively determined and/or output by the module (14). Procedure according to one of Claims 7 until 12 , characterized in that the diameter of an area of a leak is detected with an accuracy of +/- 15%.

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